more from this thinker | more from this text
Full Idea
A circular argument - one whose conclusion is to be found among its premises - is inadmissible in most informal contexts, even though it is formally valid.
Gist of Idea
Circular arguments are formally valid, though informally inadmissible
Source
Robert Hanna (Rationality and Logic [2006], 2.1)
Book Ref
Hanna,Robert: 'Rationality and Logic' [MIT 2006], p.31
A Reaction
Presumably this is a matter of conversational implicature - that you are under a conventional obligation to say things which go somewhere, rather than circling around their starting place.
| 3612 | Clear and distinct conceptions are true because a perfect God exists [Descartes] |
| 2290 | Once it is clear that there is a God who is no deceiver, I conclude that clear and distinct perceptions must be true [Descartes] |
| 3641 | It is circular to make truth depend on believing God's existence is true [Arnauld on Descartes] |
| 4524 | Descartes is right that in the Christian view only God can guarantee the reliability of senses [Nietzsche on Descartes] |
| 3659 | I know the truth that God exists and is the author of truth [Descartes] |
| 9355 | One sort of circularity presupposes a premise, the other presupposes a rule being used [Braithwaite, by Devitt] |
| 9161 | Maybe reasonableness requires circular justifications - that is one coherentist view [Field,H] |
| 11059 | Circular arguments are formally valid, though informally inadmissible [Hanna] |